SAN FRANCISCO (CBS SF) — When it comes to the Zika virus, we’ve all seen the heartbreak. Babies born with unusually small heads, and other severe brain defects.

Now Bay Area scientists have uncovered some major clues about the infection, and a possible drug that might block it.

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A mother’s womb, her placenta, is supposed to protect her developing fetus. But somehow, the Zika virus gets in, and causes terrible damage.

Now, thanks to two Bay Area teams, we have an idea on where it gets in. And how to possibly block it.

A Zika-infected mosquito bites a pregnant woman and that single bite can result in a devastating birth defect.

Professor Eva Harris heads up the team at the University of California at Berkeley.

“We’re able to actually identify what are the cells that are infected with Zika and how is it that we can have inhibitors that can block that infection,” Harris said.

Professor Lenore Pereira oversees the team at the University of California at San Francisco.

“This was very surprising for us. We didn’t know what to expect honestly and this was very rewarding,” Pereira said.

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Together the teams have discovered how the Zika virus targets certain cells in a woman’s placenta in order to harm her developing fetus.

“If you understand which cell is targeted, you can know perhaps how one can block infection,” Pereira explains.

In lab dishes, the scientists used two strains of the Zika virus and about fifty placentas from women who delivered at UCSF.

They found how Zika infects placental cells by two different routes: one in early pregnancy – where the placenta attaches to the uterine wall and beginning in the second trimester – through late pregnancy – by a second route – through the membrane which forms the amniotic sac.

The scientists then discovered how the virus can be blocked from entering these cells with an antibiotic called Duramycin.

Pereira said, “This particular drug actually works against the virus itself.”

Duramycin is currently approved for use in animals, and not humans.

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Experts say Duramycin may not be safe to use in pregnant women, but how this drug works to block infection may serve as a model to design a drug that will work and be safe.

Veronica De La Cruz